deploy: only generated content in deploy/kubernetes-*

Mixing manually created symlinks and generated files in the same
directory made it difficult to maintain the deploy/kubernetes-*
directories. The symlinks themselves were problematic for "kubectl
create -f https://..." because that only worked for raw URLs that
referred to files, but not for symlinks.

Now all Kubernetes directories are created from scratch by "make
kustomize". The Makefile rules get simplified to avoid repetition.

Makefile

@@ -153,42 +153,59 @@ _work/kustomize: _work/kustomize_${KUSTOMIZE_VERSION}_linux_amd64.tar.gz
 # output.
 KUSTOMIZE_INPUT := $(shell [ ! -d deploy/kustomize ] || find deploy/kustomize -type f)
 
-# Output files and their corresponding kustomize target.
+# Output files and their corresponding kustomization, in the format <target .yaml>=<kustomization directory>
+KUSTOMIZE :=
+
+# For each supported Kubernetes version, we provide four different flavors.
 # The "testing" flavor of the generated files contains both
 # the loglevel changes and enables coverage data collection.
-KUSTOMIZE_OUTPUT :=
-KUSTOMIZE_OUTPUT += deploy/kubernetes-1.17/pmem-csi-direct.yaml
-KUSTOMIZATION_deploy/kubernetes-1.17/pmem-csi-direct.yaml = deploy/kustomize/kubernetes-base-direct
-KUSTOMIZE_OUTPUT += deploy/kubernetes-1.17/pmem-csi-lvm.yaml
-KUSTOMIZATION_deploy/kubernetes-1.17/pmem-csi-lvm.yaml = deploy/kustomize/kubernetes-base-lvm
-KUSTOMIZE_OUTPUT += deploy/kubernetes-1.17/pmem-csi-direct-testing.yaml
-KUSTOMIZATION_deploy/kubernetes-1.17/pmem-csi-direct-testing.yaml = deploy/kustomize/kubernetes-base-direct-coverage
-KUSTOMIZE_OUTPUT += deploy/kubernetes-1.17/pmem-csi-lvm-testing.yaml
-KUSTOMIZATION_deploy/kubernetes-1.17/pmem-csi-lvm-testing.yaml = deploy/kustomize/kubernetes-base-lvm-coverage
-
-KUSTOMIZE_OUTPUT += deploy/common/pmem-storageclass-ext4.yaml
-KUSTOMIZATION_deploy/common/pmem-storageclass-ext4.yaml = deploy/kustomize/storageclass-ext4
-KUSTOMIZE_OUTPUT += deploy/common/pmem-storageclass-xfs.yaml
-KUSTOMIZATION_deploy/common/pmem-storageclass-xfs.yaml = deploy/kustomize/storageclass-xfs
-KUSTOMIZE_OUTPUT += deploy/common/pmem-storageclass-cache.yaml
-KUSTOMIZATION_deploy/common/pmem-storageclass-cache.yaml = deploy/kustomize/storageclass-cache
-KUSTOMIZE_OUTPUT += deploy/common/pmem-storageclass-late-binding.yaml
-KUSTOMIZATION_deploy/common/pmem-storageclass-late-binding.yaml = deploy/kustomize/storageclass-late-binding
-KUSTOMIZE_OUTPUT += deploy/operator/pmem-csi-operator.yaml
-KUSTOMIZATION_deploy/operator/pmem-csi-operator.yaml = deploy/kustomize/operator
-kustomize: _work/go-bindata clean_kustomize_output $(KUSTOMIZE_OUTPUT)
-	$< -o deploy/bindata_generated.go -pkg deploy deploy/kubernetes-*/*/pmem-csi.yaml
+KUSTOMIZE_KUBERNETES_OUTPUT = \
+    deploy/kubernetes-X.XX/pmem-csi-direct.yaml=deploy/kustomize/kubernetes-base-direct \
+    deploy/kubernetes-X.XX/pmem-csi-lvm.yaml=deploy/kustomize/kubernetes-base-lvm \
+    deploy/kubernetes-X.XX/pmem-csi-direct-testing.yaml=deploy/kustomize/kubernetes-base-direct-coverage \
+    deploy/kubernetes-X.XX/pmem-csi-lvm-testing.yaml=deploy/kustomize/kubernetes-base-lvm-coverage \
+
+KUSTOMIZE_KUBERNETES_VERSIONS = \
+    1.17 \
+    1.18 \
+    1.19 \
+
+KUSTOMIZE += $(foreach version,$(KUSTOMIZE_KUBERNETES_VERSIONS),$(subst X.XX,$(version),$(KUSTOMIZE_KUBERNETES_OUTPUT)))
+
+KUSTOMIZE += deploy/common/pmem-storageclass-ext4.yaml=deploy/kustomize/storageclass-ext4
+KUSTOMIZE += deploy/common/pmem-storageclass-xfs.yaml=deploy/kustomize/storageclass-xfs
+KUSTOMIZE += deploy/common/pmem-storageclass-cache.yaml=deploy/kustomize/storageclass-cache
+KUSTOMIZE += deploy/common/pmem-storageclass-late-binding.yaml=deploy/kustomize/storageclass-late-binding
+KUSTOMIZE += deploy/operator/pmem-csi-operator.yaml=deploy/kustomize/operator
+
+KUSTOMIZE_OUTPUT := $(foreach item,$(KUSTOMIZE),$(firstword $(subst =, ,$(item))))
+
+# This function takes the name of a .yaml output file and returns the
+# corresponding kustomization as specified in KUSTOMIZE. It works by
+# iterating over all items and only return the second half of the
+# right one.
+KUSTOMIZE_LOOKUP_KUSTOMIZATION = $(strip $(foreach item,$(KUSTOMIZE),$(if $(filter $(1)=%,$(item)),$(word 2,$(subst =, ,$(item))))))
+
+# This function takes the kustomize binary and the name of an output
+# file as arguments and returns the command which produces that file
+# as stdout.
+KUSTOMIZE_INVOCATION = (echo '\# Generated with "make kustomize", do not edit!'; echo; $(1) build --load_restrictor none $(call KUSTOMIZE_LOOKUP_KUSTOMIZATION,$(2)))
 
 $(KUSTOMIZE_OUTPUT): _work/kustomize $(KUSTOMIZE_INPUT)
-	(echo '# Generated with "make kustomize", do not edit!'; echo; $< build --load_restrictor none $(KUSTOMIZATION_$@)) >$@
+	mkdir -p ${@D}
+	$(call KUSTOMIZE_INVOCATION,$<,$@) >$@
 	if echo "$@" | grep '/pmem-csi-' | grep -qv '\-operator'; then \
-		dir=$$(echo "$@" | tr - / | sed -e 's;kubernetes/;kubernetes-;' -e 's/.yaml//' -e 's;/pmem/csi/;/;') && \
+		dir=$$(echo "$@" | tr - / | sed -e 's;kubernetes/;kubernetes-;' -e 's;/alpha/;-alpha/;' -e 's/.yaml//' -e 's;/pmem/csi/;/;') && \
 		mkdir -p $$dir && \
 		cp $@ $$dir/pmem-csi.yaml && \
 		echo 'resources: [ pmem-csi.yaml ]' > $$dir/kustomization.yaml; \
 	fi
 
+kustomize: _work/go-bindata clean_kustomize_output $(KUSTOMIZE_OUTPUT)
+	$< -o deploy/bindata_generated.go -pkg deploy deploy/kubernetes-*/*/pmem-csi.yaml
+
 clean_kustomize_output:
+	rm -rf deploy/kubernetes-*
 	rm -f $(KUSTOMIZE_OUTPUT)
 
 # Always re-generate the output files because "git rebase" might have
@@ -212,7 +229,7 @@ _work/go-bindata:
 test: test-kustomize
 test-kustomize: $(addprefix test-kustomize-,$(KUSTOMIZE_OUTPUT))
 $(addprefix test-kustomize-,$(KUSTOMIZE_OUTPUT)): test-kustomize-%: _work/kustomize
-	@ if ! diff <($< build --load_restrictor none $(KUSTOMIZATION_$*)) $*; then echo "$* was modified manually" && false; fi
+	if ! diff <($(call KUSTOMIZE_INVOCATION,$<,$*)) $*; then echo "$* was modified manually" && false; fi
 
 # Targets in the makefile can depend on check-go-version-<path to go binary>
 # to trigger a warning if the x.y version of that binary does not match